Digital circuits are utilized to implement a wide variety of functions. Filters are commonly implemented with digital circuitry because of the precision and accuracy attained as opposed to analog circuitry. A well known digital filter is the finite impulse response (FIR) filter which is particularly useful in telecommunications. The FIR filtering process is a weighted moving average of previous data values, and the FIR filtering equation is an accumulation of an integer number of product terms. A special class of filters which may be implemented with an FIR filter is an adaptive filter. An adaptive filter provides an error signal which represents the difference between a desired signal and an estimate of the desired signal. The accuracy of FIR fiters and adaptive filters is proportional to the number of recent data samples, referred to as "filter taps", which are stored by the filter. Since data storage is limited in each filter circuit, others have coupled together or cascaded filter circuits, each implemented by a discrete integrated circuit, to provide a single filter structure with a very large number of taps. Unfortunately, partial sums are generated by each integrated circuit and the partial sums must be added external to the integrated circuits. Not only is additional external summing circuitry required, but filter speed is reduced due to delays inherent in adding the partial sums.